Attention Deficit Hyperactivity Disorder (ADHD) is primarily characterized by inattention, restlessness (hyperactivity) and impulsivity. Children and adolescents with ADHD have some impairment in their social and school life throughout development such as poor academic performance, repetition, suspension, difficult relationship with family and peers and low tolerance for frustration [1].

Among the comorbidities, studies relate the body weight [2], cognitive deficit [3, 4] and motor difficulties with ADHD [1]. Children with ADHD presents more risk behavior than those without this disorder [5].

Treatment usually consists of guidelines for parents and teachers with or without drug administration [6, 7, 8]. However, according to recent studies [9], exercise provides beneficial changes such as decreased risk of chronic degenerative diseases, increased bone mineral density and cardiorespiratory benefits. Recently, improvement in cognitive function was also discovered. The hormones that regulate memory (catecholamines) are also involved in the homeostatic regulation of exercise [9, 10]. These surveys showed that the release of catecholamines, vasopressin, ACTH and B-endorphin is stimulated by exercise, which proves the relationship between intense exercise and memory regulation.

Several researchers have sought to determine the influence of external stimuli on attention in children with ADHD. Studies have shown that specific colors [11] and even body vibration [12] are relevant to the performance of people with this disorder.

Therefore, the hypothesis that the attention of ADHD children can be improved using physical activity has been proposed. Therapists have indicated physical activity to prevent several comorbidities [9, 13]; however, there is no quantitative comparison of the obtained benefits.

Thus, this work aims to quantify the effect of physical activity on the attention of children with ADHD.

The task of the relay race was performed with GE-EF and GC-EF on different days but at the same hour. Each volunteer ran without rest for 5 min and took an average of 15 balloons. After the physical exercise, the volunteers underwent a test match, and the time was recorded. Table 2 presents the sum of spend time for each task of game by all groups.

Table 3 shows the average time (in seconds) that was taken for each task group in the game.

Table 4 shows the respective relative percentages for the participants to complete each task in the function of the GC group.

The GE-EF and CG groups showed approximately the identical performance compared to the complete game, with a small standard deviation, which proves the sample homogeneity. Fig 4 shows the percentage differences between GE-EF and GC. Fig 5 shows the percentage difference between GE-EF and GE in the entire game.

Table 5 shows the sum of the average total duration of each group to complete the game.

Fig 6 shows the sum with the standard deviation of each group to complete the game.

The group with ADHD and that participated in the proposed physical activity (GE-EF) obtained 30.52% better performance than the group with signs of ADHD that did not participate in physical activity (GE) and 40.36% better than the group without characteristic of ADHD that participated in physical activity (GC-EF). The group that more rapidly reached the goal proposed by the assessment game was that group without characteristic of ADHD and not involved in physical activity proposed (GC), ending the testing game 2.5% faster than the GE-EF group.

Regarding the normal distribution analysis, D'Agostino test was applied allowing that the investigators identify that the sampling distribution is non-parametric. In addition, Kruskal-Wallis test was used showing significant differences between groups (H = 32.2207, p ≤ 0.0001). It was followed by the Post-hoc Dunn test, where significant differences between groups were also identified. See Table 6 for details.

As the time for performing each task was obtained discretely, the Matlab software was used to construct computational routines that allow generating continuity depending on time (Fig 7).

The results of this study showed that the GE-EF and GC groups overall had similar performances. The software's second stage (tasks 9 to 18) was contextualized in a minefield, where the player with better concentration throughout the tasks is favored (in this case GC had high-performance). Therefore, the volunteers from the GE-EF presented better results in the software's first stage (tasks 1–9), which suggests that this phase is favored by an exploratory behavior, which is an intrinsic characteristic of the subjects with ADHD.

Many variables can affect the collected information in computer games, such as ability to use the command interface, intensive practice in computer games or even lack of collaboration and intellectual level of participants [4]. In our study, we selected volunteers who had similar skills in games and academic performance. The students with the best and worst grades in several disciplines were left out of this study. This step allowed for a standard derivation of less than 5% for task execution time in the same group. Therefore, we believe that our method is not susceptible to uncontrolled variables.

The results of this study also show that the GC group has a performance that is 42% better than the GC-EF group. These data seem indicate that after an intense physical exercise, people without ADHD show impairment in attention performance. However, this hypothesis requires further studies, which include the assessment of the duration of this effect.

The computer game “Raiders of the Lost Treasure” [11] allowed us to generate measurable records and showed the improved attention of the students with ADHD that experienced intense exercise in a short time interval (approximately 5 min). Therefore, children with ADHD symptoms may have equivalent concentration to individuals without the disorder after physical exertion. Over past decades, several studies on humans [9, 17, 18] have demonstrated the benefits of exercise on health and brain function. These authors clarify that regular exercise can protect the brain against disease and certain types of brain injuries because many positive effects occur in the hippocampus, which is important region for learning and memory.

Lim et al. [19] used a training system with a more intensive game for 20 unmedicated children with ADHD and significant symptoms of inattention. The treatment consisted of eight weeks of training with 24 sessions followed by three monthly booster training sessions. In Lim et al. [20], the game for attention training was considered a new potential treatment for ADHD.

Fuermaier et al. [12] explored the effects of whole-body vibration on attention in healthy individuals and adults who were diagnosed with ADHD. The authors used the beneficial effects of whole-body vibration on various physiological measures. Treatment was passively performed while the volunteers were seated in a chair that was placed on a vibration platform. Fuermaier et al. [12] showed significant beneficial effects of small to medium size for all volunteers and improved cognitive performance of healthy volunteers and those with ADHD after 2 min of treatment. All volunteers in this study were subjected to intense physical exercise, which increased their maximum heart rate from 65% to 85% and made them tired and euphoric in the end. Physical activity increases the release of serotonin, dopamine and norepinephrine, and the increase in these neurotransmitters makes the normal volunteers more excited after the physical activity. With their decrease, the volunteers calm down and return to focus and have normalized attention. Therefore, it is assumed that the attention of the subjects with ADHD is improved because of the release of these neurotransmitters. These data corroborate with other studies [21], which report that physical exercise helps building the mechanism that increases the amount of neurotransmitters in the brain and their postsynaptic receptors. During the physical activity, more neurotransmitters (dopamine, serotonin and norepinephrine, as well as other molecules) are released and may regulate this imbalance. Exercise improves the mood, well-being, anxiety and depression and helps one cope better with stress.

A physical education survey [18] observed that physical exercise can reduce anxiety symptoms. The effect was independent of physical fitness, although the anxiety levels were lower in the group that achieved better aerobic fitness during the treatment.

Medina et al. [9] examined the possibility that physical exercise improved the sustained attention in children with ADHD and tested the hypothesis of the interaction of catecholamines and their receptors in the prefrontal cortex and striatal areas in cognitive improvement that was acutely induced by effort. The children's attention immediately after exercise was compared to assess the chronic effects of psychostimulants and whether they caused some change in test-II Conner's Continuous Performance (CPT) immediately after exercise. The results of Medina et al. [9] showed that exercise resulted in higher alertness, decreased impulsiveness, increased reaction speed and greater stability in all aforementioned metrics. Our study shows that physical activity also improves the performance of children in tasks that require attention.

This study confirms the hypothesis of Medina et al. [9] and Koehl et al. [10]: intense physical exercise improves the attention of children and adolescents with ADHD symptoms. Physical exercise may be helpful for their learning because attention is essential to the school performance of any individual.

Physical exercises help improve children's attention and provide greater impulse control; these additional effects appear almost immediately, as confirmed in this study, which helps the concentration of children with ADHD.